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§477. Installation of Containers.

(a) Aboveground Containers.

(1) Metallic structural supports, when used, shall be encased in concrete or other material having a fire-resistant rating of at least 2 hours when the distance between the lower surface of the tank and the top of the concrete or masonry foundation exceeds 18 inches.

(2) Aboveground storage containers shall be protected from impact from vehicles by means of crashposts, curbs, fences, railings or similar barriers. Where crashposts are used, they shall be no less than 5 feet long with 2 feet below ground and encased in concrete. Posts shall be no less than 4 inches in diameter and be filled with concrete if the wall thickness is less than that of standard pipe. Posts shall be 4 feet apart on centers (maximum) and at least 3 feet from the storage container. Other materials may be used and shall provide equivalent protection. Such curbs or fences shall be arranged so they will not hamper free ventilation around the containers.

(3) Containers installed in battery shall not be installed with liquid and vapor lines connecting into common headers unless either:

(A) the working pressure of all such containers is at least equal to the vapor pressure of the product stored in any such container; or,

(B) check valves or other devices are installed in the system to prohibit the introduction of the higher-pressure product into the lower-pressure container.

(b) Mounded Containers.

Containers shall not be mounded unless written permission to do so has been obtained from the Division.

In addition to the requirements of NFPA 58, Section 3-2.4.7, the following construction, maintenance, and documentation provisions shall apply:

(1) Construction.

(A) Where containers are to be installed closer than 30 inches above surrounding grade, a moisture barrier to prevent the upward migration of potentially corrosive salts or acids shall be installed.

(B) Drainage tile or pipe shall be installed to prevent the accumulation of moisture within the insulating medium. Where a moisture barrier is installed, the drainage material shall be placed above that barrier.

(C) Relief-valve capacity and installation shall be that which is required for aboveground containers and shall comply with NFPA 58, Section 3-2.6.3, as measured from the tank shell.

NOTE: Access crawlways shall be evaluated for compliance with the General Industry Safety Orders, Article 108.

(F) Prior to mounding, inaccessible plugged openings, joints, and other appurtenances shall be tested for leaks at operating pressure.

(G) Liquid level and pressure gauges shall be accessible visually and physically and shall be vented outside of the mounding.

(H) Mounded containers shall be protected against corrosion by coating the container with corrosion-resistant material approved for buried installations provided the material is applied in accordance with the manufacturer's recommendations. The employer/user shall submit to the Division a copy of the manufacturer's data for the coating material showing the method and procedures for coating prior to installation.

(I) All containers shall be cathodically protected and electrically isolated from connecting piping or electrically conducive structures in accordance with good engineering practice.

(J) Depth gauges shall be installed at intervals of not greater than 6 feet along the vertical center line of the container to visually indicate when insulating material becomes less than 1 foot in depth over the container.

(2) Maintenance Requirements.

(A) Filling densities shall be as required for aboveground containers.

(B) Voltage readings from the cathodic system shall be taken and recorded annually and shall produce a negative voltage of at least 0.85 volts with reference to a saturated copper-copper sulfide half cell.

(C) All mounded containers shall be completely uncovered for an inspection of all external surfaces at intervals of at least once every 5 years. The intervals shall be extended when no failure in the cathodic protection has been detected, provided that every container shall be uncovered at least once every 30 years. Alternate methods of inspection may be used, e.g., UT, internal inspection.

(D) Where passive cathodic protection is provided, amperage readings shall be taken annually from each sacrificial anode. Where impressed current is used, amperage and voltage readings shall be reported at 6-month intervals.

(E) The depth gauges across the top of the container shall be observed annually to determine that a minimum of one-foot coverage of insulating material exists over the top of the entire container.

(F) Leak surveys shall be conducted annually using a combustible-gas indicator or comparably effective instrument to sample the air from the drainage system beneath the container and from test holes surrounding the container at intervals not greater than 10 feet.

(3) Documentation.

(A) The following documentation shall be maintained for the life of the system:

1. The construction requirements of this Section and of NFPA 58, Section 3-2.4.7 shall be documented through the use of photographs and other appropriate means.

2. All tests required in this Section shall be recorded in a system log showing the date the tests were taken, the related readings, and the name of the person making the tests. These tests shall be available to the Division at any time for the purpose of inspection and verification and shall be retained for the life of the installation.

3. The owner or operator of a mounded container shall send a copy of the system log for that container to the Division's principal safety engineer each year during the month of June.

(c) Underground Containers.

Containers shall not be installed underground unless written permission to do so has been obtained from the Division.

In addition to the requirements of NFPA 58, Section 3-2.4.8, the following construction, maintenance, and documentation provisions shall apply:

(1) Construction.

(A) Underground containers shall be protected against corrosion by coating the container with corrosion-resistant material approved for buried installations provided the material is applied in accordance with the manufacturer's recommendations. The employer/user shall submit to the Division a copy of the manufacturer's data for the coating material showing the method and procedures for coating prior to installation.

(B) All containers shall be cathodically protected and shall be electrically isolated from connecting piping or electrically conducive structures in accordance with good engineering practice.

(C) No tank used underground shall be installed aboveground until it has been inspected and found to be in compliance with requirements for an aboveground installation.

(2) Maintenance Requirements.

(A) Voltage readings from the cathodic system shall be taken and recorded annually and shall produce a negative voltage of at least 0.85 volts with reference to a saturated copper-copper sulfite half cell.

(B) All underground containers shall be completely uncovered for an inspection of all external surfaces at intervals of at least once every 5 years. The intervals shall be extended when no failure in the cathodic protection has been detected, provided that every container shall be uncovered at least once every 30 years.

Alternate methods of inspection such as internal inspection and ultrasonic testing may be used to check and verify the integrity of the container in lieu of it being uncovered.

(C) Where impressed current is used, amperage and voltage readings shall be recorded at 6-month intervals.

(D) Leak surveys shall be conducted annually using a combustible-gas indicator or comparably effective instrument to sample the air from the tests holes surrounding the container at intervals not greater than 10 feet.

(3) Documentation.

(A) The following documentation shall be maintained for the life of the system:

1. The construction requirements of this Section and NFPA 58, Section 3-2.4.8 shall be documented through the use of photographs and other appropriate means.

2. All tests required in this Section shall be recorded in a system log showing the date the tests were taken, the related readings, and the name of the person making the tests. These tests shall be available to the Division at any time for the purpose of inspection and verification and shall be retained for the life of the installation.

3. The owner or operator of a underground container shall send a copy of the system log for that container to the Division's principal safety engineer each year during the month of June.